Running 315's for steers

My bad, my understanding was that the set up in question was the cozad on your pic. Seems a little overkill to use a double frame heavy haul truck with a stepdeck. Have you tried running shorter mudflaps?

As far as getting more weight on the steer, do you think you could add another kingpin position to your trailer? I've done it previously to a 53 ft step with a long frame truck to keep it from needing an overlength permit.

 

Well I just measured my distance from center of steer axle to where my king pin is now. 19' 6"
I currently have 13800 on my steers. I have a 265 wheel base. I have about 6 more inches I can slid forward on my slider, but with this trl. I'm currently pulling I can only slide up about another 2"
Hope this might help you some.
Like I posted prior I'm running 3 axles on the back. My rear axle spacings are 4' 7"

 

I don't see cutting frame gaining you anything. I see cutting frame creating a new problem. Drive tires hitting frame of trailer when turning, especially on uneven ground.

What rears are on the truck?

Where is the fifth wheel pin location when the fifth wheel is all the way up?

Where is the fifth wheel pin location when slid all the way back?

How long is the slider?

What's the swing clearance of the neck of the trailer?

What is the top deck length of the stepdeck?

 

So are you just talking about when you haul 80K lbs? If so, then dont even think about putting more than 12300 lbs on the steers. You will never have the need running that light. Do you have dual leveling valves on the drives?

 

Why not more than 12300 on his steer?
He posted he has a 14k axle I believe.
Heck even mty I have than 12 on my steers

 

If he is only hauling 80K, then its a waist of time to cut the frame of the truck to get the fifth wheel forward. The other thing you can try is higher ply/load rating steer tires. The sidewall is stiffer and will respond better.

 

Good point bringing up the leveling valves on the drives. That's where I started to go when I asked him about axle weight numbers, depending in his load, but got distracted.

The part that I still question is the OP's statement about the "nose-up" attitude the truck sits when loaded to 80k. And his questioning if he raised it an additional 1.5" if that would be "better".
My question to the OP is... did you do anything to the front suspension to raise it any? Do you have air suspension on front, possibly aftermarket like the Timbren units?
Why did you ask about raising the front? (That would be the opposite direction you'd want to go for more weight on front axle, less on drives).

Why is his front end going "nose-up" on hooking to a load? Seems to me his leveling valves are either not functioning properly, not correctly adjusted or binding, and possibly in combination with the fifth wheel kingpin position being just a bit too far rearward.

 

Personally I doubt the 315's will change the "feel" from the front end but you definitely need to address the issue on the 5th wheel. A shorter king pin set back on the trailer, neck extension something so you can slide the 5th wheel forward to balance some of the load.

 

Studied your pics for a minute and I came up wth a couple options

1. Shove the fuel tanks forward.

2. Kinda of iffy, but it should help with your issue: Go to a Canadian spread on your drives. Go from 4'4 to a 6 ft spread between the drives. Might make it a little rougher to make tight turns (and with your wheelbase, you're probably already having an issue there), and your tyres on the front drive axle will wear quicker...

these options shouldn't add any weight to the truck, and will probably give you a better ride and handling characteristics.